Small intestine can sense and react to bitter toxins in food

October 9, 2008

Toxins in food often have a bad, bitter taste that makes people want to spit them out. New UC Irvine research finds that bitterness also slows the digestive process, keeping bad food in the stomach longer and increasing the chances that it will be expelled.

This second line of defense in the gut against dietary toxins also triggers the production of a hormone that makes people feel full, presumably to keep them from eating more of the toxic food.

This discovery has the potential to help scientists develop better therapies for ailments ranging from cancer to diabetes, and it may explain why certain isolated populations around the world have adapted to eat and enjoy local foods that taste bad to outsiders and make them sick.

The study, appearing online Oct. 9 in the Journal of Clinical Investigation, was performed with mice, and the results probably translate to humans, said Timothy Osborne, molecular biology and biochemistry professor and study senior author.

"We have evolved mechanisms to combat the ingestion of toxins in our food," Osborne said. "This provides a framework for an entirely new area of research on how our bodies respond to what is present in our diets."

Mammals have evolved to dislike the bitter taste of toxins in food. This response is particularly important when they eat a lot of plant material, which tends to contain more bitter-tasting, potentially toxic ingredients than meat.

Examples of bitter-tasting toxins include phenylthiourea, a compound that destroys the thyroid gland, and quinine, found in tonic water, which can be deadly in large doses.

If toxins are swallowed, bitter-taste receptors in the gut sense them and trigger the production of a hormone called cholecystokinin that both suppresses appetite and slows the movement of food from the stomach to the small intestine.

Interestingly, the UCI scientists found that cholesterol regulates the activity of bitter-taste receptors in the intestine, and diets high in plant material and potential toxins naturally are low in cholesterol, compared to low-toxin, high-cholesterol, meat-based diets.

In small intestine cell cultures, low levels of cholesterol triggered a stronger receptor response – meaning they worked better – while high levels caused a weaker response.

The same response was observed in mice that were given drugs to stop the production and absorption of cholesterol. Not only were their receptors more active, their small intestine cells produced two to three times the amount of the appetite-suppressing hormone in the presence of bitter food, compared to normal mice.

Scientists say that regulation of taste receptors by dietary constituents likely explains why groups of people taste certain foods differently.

"One group of people may think something tastes great and can metabolize it just fine, but a group from the outside may think it tastes horrible and get sick," Osborne said. "The first group likely adapted to the food through a change in the expression and pattern of their dietary sensing molecules."

With this knowledge, scientists could make medicines less bitter, which in turn would allow for increased palatability and quicker absorption. Drugs used to treat cancer sometimes include molecules that taste bitter. Also, changing the patient's eating habits could improve the effectiveness of such drugs.

In addition to the appetite-suppressing hormone, bitter-taste receptors in the gut activate the production of glucagon-like peptide 1, a protein that stimulates insulin secretion in the pancreas. Drugs currently are on the market that attempt to stabilize this protein in people with diabetes, and therapies aimed at increased production are attractive therapeutic targets.

"Because bitter-taste receptors are expressed in the gut, a new avenue exists to identify ways to stimulate production of GLP-1," Osborne said. "It could be very beneficial for the treatment of diabetes and possibly other diseases."

Source: University of California - Irvine

Explore further: Raw flour can be source of shiga toxin-producing E. coli

Related Stories

Raw flour can be source of shiga toxin-producing E. coli

November 23, 2017
(HealthDay)—Raw flour can be a source of outbreak of Shiga toxin-producing Escherichia coli (STEC) infections, according to a study published in the Nov. 23 issue of the New England Journal of Medicine.

Proper food preparation can prevent botulism

April 30, 2015
A recent deadly outbreak of botulism in Ohio underscores the necessity for proper home canning procedures and food preparation, a University of Georgia Extension food safety specialist said.

Bitter taste perception is not just about flavors, geneticists show

December 6, 2011
Long the bane of picky eaters everywhere, broccoli's taste is not just a matter of having a cultured palate; some people can easily taste a bitter compound in the vegetable that others have difficulty detecting. Now a team ...

A trained palate: Understanding complexities of taste, smell could lead to improved diet

May 30, 2012
Researchers at Oregon State University have made some fundamental discoveries about how people taste, smell and detect flavor, and why they love some foods much more than others.

Nestle to boost study of harmful food infections

May 30, 2013
(AP)—Nestle SA, the world's biggest food and drink company, is boosting research to tackle the threat of ever-stronger strains of bacteria and germs in food manufacturing.

Fish like grouper, barracuda may pose food-poisoning risk

January 31, 2013
(HealthDay)—People who eat large, tropical predatory reef fish such as barracuda and grouper may be at risk for a form of food poisoning called ciguatera fish poisoning, U.S. health officials reported Thursday.

Recommended for you

How defeating THOR could bring a hammer down on cancer

December 14, 2017
It turns out Thor, the Norse god of thunder and the Marvel superhero, has special powers when it comes to cancer too.

Researchers track muscle stem cell dynamics in response to injury and aging

December 14, 2017
A new study led by researchers at Sanford Burnham Prebys Medical Discovery Institute (SBP) describes the biology behind why muscle stem cells respond differently to aging or injury. The findings, published in Cell Stem Cell, ...

'Human chronobiome' study informs timing of drug delivery, precision medicine approaches

December 13, 2017
Symptoms and efficacy of medications—and indeed, many aspects of the human body itself—vary by time of day. Physicians tell patients to take their statins at bedtime because the related liver enzymes are more active during ...

Time of day affects severity of autoimmune disease

December 12, 2017
Insights into how the body clock and time of day influence immune responses are revealed today in a study published in leading international journal Nature Communications. Understanding the effect of the interplay between ...

Estrogen discovery could shed new light on fertility problems

December 12, 2017
Estrogen produced in the brain is necessary for ovulation in monkeys, according to researchers at the University of Wisconsin-Madison who have upended the traditional understanding of the hormonal cascade that leads to release ...

3-D printed microfibers could provide structure for artificially grown body parts

December 12, 2017
Much as a frame provides structural support for a house and the chassis provides strength and shape for a car, a team of Penn State engineers believe they have a way to create the structural framework for growing living tissue ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.